How to deal with perscription drug addition?

I have been in a relationship with a rather exterordinary women. She has a drug addition. She has went to treatment twice and so far it appears that nothing is working. im very worried and im asking, how can she deal with her addition? I have tried a long time to show her a better life then her drugs. but time and again she has chosen her pills over our relationship. Please any information would be greatly appreciated.